Silica-Silver Colloid for Stable Biocidal Dispersion
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Solution Overview
Problem
Existing colloidal silver dispersions face challenges with low biocidal activity due to poor dispersion of silver ions and rapid leachability, requiring high concentrations and specific particle size control for effective applications.
Innovation Solution
The development of colloidal nano-composites where silver ions are adsorbed onto the surface of silica particles, achieving high concentrations and tailored particle size distributions, ensuring stable and non-leachable biocidal activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional colloidal silver dispersions are used, then silver ions are released quickly (high leachability), but biocidal activity is reduced and effectiveness is short-lived
Solution Approach 1:
The patent creates a composite material where silver ions are adsorbed onto silica particles, forming a silver-silica composite colloid. This composite structure allows the silver ions to be retained on the particle surfaces while maintaining biocidal activity, solving the problem of rapid leachability and short duration of action.
Solution Approach 2:
The silica particles act as an intermediary carrier that holds the silver ions on their surfaces. This intermediary structure prevents direct release of silver ions into the environment while maintaining their biocidal functionality, thereby extending the duration of effectiveness.
2Reliability
If high concentrations of silver are used to maintain biocidal activity, then effectiveness is improved, but cost and potential harm increase
Solution Approach 1:
The patent applies local quality by concentrating silver ions specifically on the surfaces of silica particles rather than distributing them uniformly throughout the solution. This localized arrangement maximizes biocidal activity at the particle surfaces where it is most effective, reducing the overall silver concentration needed while maintaining effectiveness.
Solution Approach 2:
The silver-silica composite structure allows for high silver concentration on particle surfaces while maintaining stable dispersion in the colloid. This composite approach enables effective biocidal activity with reduced total silver usage compared to conventional dispersions.
3Reliability
If silver ions are highly dispersed in solution, then biocidal activity is enhanced, but leachability and unwanted release increase
Solution Approach 1:
The silica particles serve as an intermediary that provides a stable platform for silver ion adsorption. This intermediary structure maintains high dispersion of silver ions on particle surfaces for enhanced biocidal activity, while simultaneously preventing unwanted release into the environment through the stable particle-colloid system.
Solution Approach 2:
The patent utilizes the stable colloid system as a disposable carrier that releases silver ions controlledly over time. The silica particle-colloid system acts as a temporary reservoir that maintains silver ion dispersion without causing unwanted release, effectively balancing biocidal activity with controlled delivery.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for high biocidal activity with reduced silver usage, maintaining effectiveness over time and preventing precipitation, even at high pH levels, while maintaining stability and preventing unwanted silver ion release.
Implementation Method 1
silver ions are adsorbed onto the surface of silica particles
Data Source
AI summary
A colloidal dispersion having carrier particles of silica having a particle size from 3 nm to 100 nm to which silver ions have been adsorbed, preferably in an amount of 0.0005-5 silver ions per nm2 of silica particle surface. The surface of the carrier particles of silica suitably contains aluminumsilicate sites. It also relates to a process for making a colloidal dispersion comprising providing a silica sol, adding a solution of silver nitrate to the silica sol under agitation yielding a colloidal dispersion with silver ions adsorbed on the surface of the silica particles. The dispersion is usable as a biocide in e.g. coatings, adhesives and sealants, in surface treatment and impregnation of organic materials, in surface treatment and impregnation of inorganic materials, in textiles, garments and shoes, in medical disposables, in plastics and rubbers, in water and air purification, and in crop protection.